let lazyload = function() {
    let temp1 = window.innerHeight || document.documentElement.clientHeight
    let temp2 = document.body.scrollTop || document.documentElement.scrollTop
    let totalHeight = temp1 || temp2
    let imgsObj = $('img')
    imgsObj.each((i, item) => {
        if (item.offsetTop < totalHeight) {
            item.src = $(item).attr('src-real')
        }
    })
}
lazyload()
$(window).scroll(lazyload)